Chapter 34 Vertebrate Diversity
Dec 25, 2015
Phylum ChordataBilaterian deuterostomesDerived characteristics
NotochordIn all embryos and some adults, between digestive tube and
nerve cordProvides skeletal support, reduced in humans to vertebral
discsDorsal hollow nerve cord
Roll of ectoderm that is unique to chordates becomes CNSPharyngeal slits or clefts
Series of pouches along the pharynx that open to the outside of the body
Filter feeding in invertebrates and gas exchange in vertebratesMuscular, post-anal tail
Reduced in many speciesPropels many aquatic species
Subphylum CephalochordataLancelets have a
bladelike shapeRetain all 4
characteristics of chordates as adults
Filter feedersGas exchange across
bodyMuscles for movement
in and out of sand
Subphylum Urochordata
Tunicates or sea squirtsShort larval stage is a motile bilateraterian with all chordate
characteristicsLasts until suitable substrate found when metamorphosis occurs
Adult is sessile with degenerated NS, resorbed notocord and tail
Suspension feeders
Craniates
Chordates with a head containing a brain at anterior end of nerve cord, eyes and sensory organs
Neural crest distinguishes craniates from other chordatesCollection of cells near closing neural tube in developing
embryosCells give rise to teeth, bones of skull, facial dermis, and
neuronsPharyngeal slits into gill slits which allow sucking food and
gas exchangeHigher metabolism, extensive muscles, 2+ chamber heart,
RBC’s with hemoglobin, and kidneys
MyxiniCartilaginous skull
without jaws or vertebrae
Muscles against notocord for movement
Small brain, eyes, ears, nasal opening, and tooth-like formations of keratin
Bottom dwelling scavengers
Slime glands
VertebratesMore extensive skull Backbone of vertebrae
Encloses spinal cord and replaces notocord function
Skeletons evolved initially as unmineralized cartilageFirst structures were dental elements
Allowed animals to become scavengers and predators
Aquatic species developed dorsal, ventral, and anal fins to provide steering control
More efficient means of gas exchange
Lampreys
Parasites clamp on with jawless mouth and bore into fish to suck blood
Larvae is freshwater filter feederSome feed as larvae only before reproducing and dying
Cartilaginous skeleton with no collagen in its matrixNotocord is main axial structure surrounded by cartilage
Dorsal projections partially enclosing nerve cord
Gnathostomes
Jawed animals that are aided by teeth to grip and slice foodEvolved from skeletal rods that supported anterior gill slits
Forebrain enlargement associated with enhanced vision and smell
Lateral line systemOrgans form rows on either side of body and sense vibrations in
waterPaired fins and tail enhance swimming after prey
Class ChondrichthyansEndokeleton composed of
cartilage and Ca+
Bone traces in scales, teeth, and vertebrae surfaces
SharksSwift, but unagile awimmersBouyancy from oil stored in liver,
but must stay swimmingContinually replace teeth as lostSpiral valve increases SA of
digestive tractEnhanced sensesInternal fertilization of eggs
Oviparous: lay eggs in protective cases that hatch outside mother
Ovoviviparous: retain fertilized eggs in oviducts, nourished by yolk
Viviparous: develop in uterus provide nutrients through a placenta
Rays
Class OsteichthyansOssified endoskeleton with matrix of calcium
phosphateGills for gas exchange, protected by an
operculumBuoyancy from a swim bladder, or air sac,
with gas exchange to control rise and fallSkin covered by bony scalesSkin glands secrete mucus to skin to reduce
dragMost species are oviparous
Reproduce by external fertilization after female sheds eggs
ActinopterygiiRay-finned fishesModified for
maneuvering and defense
Originated in fresh water and spread to seasSalmon and trout
between salt and fresh water
Human source of protein
SarcopterygiiLobe-fin fishesMuscle surrounds rod-
shaped bonesFor swimming and
‘walking’ across underwater substrate
Coelacanths still survivePreviously thought
extinctLungfishes
Surface to breathe, but gills for gas exchange
Tetrapods
TetrapodsLimbs that support weight
on landDigits on feet to create
forces with groundHead separated from neck
1 vertebrae allowed up and down, 2 allowed side to side
Pelvic girdle fused to backbone to transfer leg forces to body
Pharyngeal slits become ears and glands
Class AmphibiaSalamanders and newts
Some entirely aquatic, others on land or throughout life
On land use side-to-side motionFrogs and toads
Hind legs to jumpInsects and prey caught with tongueSkin glands secrete mucous for
protectionColor variations as warnings or
camouflageCaecilian
Legless and nearly blindAbsence of legs are secondary
adaptations
‘Amphibians’Life on land and waterHerbivorous tadpole is the larval stage of frogs
Has gills, lateral line system, and long finned tail; no legsMetamorphosis into a carnivorous adult
Develops legs, lungs, external ear drums, and a digestive system; lost gills and lateral line system
Salamander and caecilian larvae resemble adult and both stages carnivorous
Necessary for skin to stay moist for gas exchangeExternal fertilization in frogs
Eggs laid in moist environments to prevent desiccationOviparous and viviparous species
Complex social behavior, ectothermic, cloaca, and 3-chambered heart
AmniotesAmniotic egg with 4
membranesDevelop from tissue layers
growing from embryoAllows embryonic
development on landEggs with shells
Differs in birds and reptilesMammals develop embryo
without egg inside femaleRib cage helps ventilate
lungsAbandon skin breathing and
conserve water
Class ReptiliaScales of keratin to protect from desiccation and
abrasionEggs on land after internal fertilization
ViviparousEctotherms use heat absorbing behavior instead
of metabolism to regulate body temperature Turtles
Box-like shields fused to vertebrae, clavicles, and ribsNeck retraction is horizontal or vertical Incubation temperature can determine sex
Crocodilians4 chambered hearts and developed kidneys for
excretionLizards
Often carnivorous
SnakesForce for movement from bending against
objects to move forwardLack ears, but sensitive to ground
vibrationsInfrared detectionAll carnivorous with teeth for griping and/or
injecting venomJacobs organFlexible airway, loosely articulated jaw, and
elastic skin to swallow prey
Class AvesFeatures adapted for flightLack urinary bladders, females with 1 ovary, reduced gonads in
both sexes except in breeding season, lightened bones, and toothless
Feathers are β-keratin (modified scales) arranged into airfoilsSome adapted for soaring others require constant flappingFlightless birds are missing sternal keel and developed muscles
Enhanced hunting and scavenging, protection, and food resource attainment
Energetically expensiveEndothermic animals with layers of fat to provide insulation
Efficient respiratory and circulatory system with 4-chambered heart
Acute vision and muscle control with larger brainComplex behavioral displays, often related to breeding Internal fertilization via ‘cloacal kiss’
Brooding keeps eggs warm
Class MammaliaMammary glands and hairEndothermic with high metabolic ratesEfficient respiratory and circulatory system
with 4-chambered heartDiaphragm to help ventilate lungsLarger brains and differentiated teeth3 lineages
Monotremes are egg-layingMarsupials have a pouchEutherians are placental mammals
MonotremesOnly in Australia and
New Guinea1 species of platypus4 species of echidnas
(spiny anteaters)Lay eggs, but
produce milk and have hairNo nipples, milk from
glands at belly that young suck
MarsupialsHigher metabolic rates
and nipplesGive birth to live young
Born early and complete development while nursing in pouch
Most live in AustraliaOpossums only ones in
North America
Order PrimatesOpposable thumb and big toe
Aids grasping and manipulation behaviorsAdapted for arboreal (tree-dwelling) life
Flat nails and not clawsReduced olfaction, but increased reliance on
visionSmaller noses, but larger eyes in front close together
Smaller litter size, longer gestation, increased maternal care
Fewer teeth, but specialized2 incisors, 1 canine, 3 premolars, and 3 molars in
each quadrant2 taxonomic arrangements (generally)
ProsimiansLemurs
Only in MadagascarEvolved in isolationPrimarily nocturnal
LorisesAfrica and southern AsiaAll nocturnal
TarsiersSpecialized for vertical climbing and leapingSoutheast Asia and IndonesiaDiet is almost completely animal matter
Tarsier
Loris
Ring-tailed lemur
AnthropoidsMonkeys (not monphyletic)
Active during the day and live in socialbands
Forelimbs about equal length ashindlimbs
New world All arboreal Central and South America Nostrils wide open and far apart Long prehensile tail-specialized for grasping
tree limbsOld world
Ground dwelling and arboreal Africa and Asia Lack prehensile tail Nostrils open downward
Hominoids (Apes)
Hominoids (Apes)Lack tailsLong arms and short legsMainly vegetarians
Humans are omnivorous, eating plants and animals
More flexibleLarger brain relative to body sizeHigh degree of social organization5 divisions
Hominoid DivisionsGibbons
9 species all in Southeast AsiaOnly entirely arboreal apesSmallest, lightest and most acrobaticMonogamous for life
OrangutanSolitary species in rain forests of Sumatra and BorneoLargest arboreal mammal, occasionally move on ground
GorillasLargest ape found only in African rainforestsLive in groups of up to 20Stand upright, walk on 4 legs with knuckles on the
ground
Hominoid Divisions (cont.)
Chimpanzees (and bonoboos)Knuckle walkersTropical AfricaBehavior closely mirrors humans
Make simple toolsRespond to mirrors
Can learn human sign languageHumans
Bipedal, larger brain, capable of language, thought, and complex tools